The invention may in particular be applied in the field of biomedicine, especially in the processing of signals having a physiological origin. The first targetted application concerns the analysis of esophageal contraction signals, but the method may equally be applied to any noised pulse signal.
The accompanying FIG. 1 shows the shape of peristaltic waves originating from signals to be processed (in the application in question).
At (a), the figure shows the act of swallowing which triggers a pressure variation (P) firstly giving rise to a proximity wave (b) which moves and deforms (c, d).
An analysis of the esophageal contraction signals results in measuring various quantities, such as the amplitude A of the peak, the period D of the pulse, the maximum slopes of the rise and fall fronts (dP/dt)M, the area under the curve S, etc.
Statistical analyses are also undertaken so as to obtain the number and percentages of the various types of pulses appearing in all the signals measured (peristaltic, tertiary, polyphasic waves, etc).
All these results are important factors for a clinician.
The physical entity, quality or property to be treated (pressure, PH, etc) is measured by various probes (esophageal, intestinal, PHmetric) or sensors. The signals representative of this entity are then amplified and recorded. With the arrival of the computer, the carrying out of measurements is no longer effected manually but by data processing methods. In order to do this, the signal is sampled and stored in a computer provided with display (screen) or printing means.
This technique is described in the document entitled "Computer-Aided Analysis of Human Esophageal Peristalsis-(I) Technical Description and Comparison with Manual Analysis" by Donald O. CASTELL and al and published in the journal "Digestive Diseases and Sciences", vol. 29, No 1, January 1984, pp. 65-72 and in "Computer Analysis of Human Esophageal Peristalsis and Lower Esophageal Sphincter Pressure. (II) An Interactive System for On-Line Data Collection and Analysis" by June A. CASTELL and al and published in "Digestive Diseases and Sciences", vol. 31, No. 11, November 1986, pp. 1211-1216.
In such processing methods, each pulse is defined, not by all the points constituting it, but by several parameters, such as the start and end samples and the peak (or top) sample, all samples defined by their amplitude and time of appearance.
The two articles referred to on the whole demonstrate that resorting to using a computer proves to be soundly-based and reliable to the extent that the results obtained satisfactorily match results obtained manually.
Although constituting a certain element of progress, this technique does nevertheless have a certain number of drawbacks, especially as regards that it is semi-automatic and requires the intervention of a practitioner during analysis so as to initialize the method (mainly at the start of analysis). The fundamentally non-stationary nature of the phenomena studied complicates the task involved.